African bollworm(Helicoverpa armigera) damage on beans (c) A.M. Varela, icipe
Lima bean pod borer ( Etiella Zinckenella) (c) Clemson University, USDA, www.ipmimages.org
Caterpillar of the legume pod borer(Maruca vitrata). Fully-grown caterpillars are about 15 mm long. (c) GTZ-IPM Horticulture Project. Kenya
The African bollworm (Helicoverpa armigera), the legume pod borer (Maruca vitrata = testulalis) the lima bean pod borer (Etiella zinckenella) are major pests of pigeon peas in East Africa. They feed on leaves, flowers and pods, destroying them.
The African bollworm (Helicoverpa armigera)
Caterpillars are 1.5 to 4 cm long. They bore holes on pods and feed on the seeds. Usually developing in the pods and feeding partly mature seeds.
The legume pod borer (Maruca vitrata)
The adult of the legume pod borer is a moth with a wing span of 15-30 mm. It has light-brown forewings with white markings and pearly white hindwings. Though mainly nocturnal, the moth may also be seen during the day. They lay eggs in the flowers or buds, or on the pods.
Caterpillars are whitish with black head and rows of conspicuous brown to black spots on the dorsal, lateral, and ventral surfaces of each body segment.
Fully-grown caterpillars measure about 15mm in length. They pupate in the soil. Caterpillars web leaves, flower buds and pods and feed inside the web. Flowers usually show little sign of damage until they wilt and drop.
They typically attack pods at the point of contact between two pods, or between a pod and a leaf or stem.
The lima bean pod borer
Adults of the lima bean pod borer are brown moths with a wing span of about 20-25 mm. They lay eggs singly or in small groups on immature pods. Young caterpillars bore into the pod.
They feed inside the pod reaching a length of 12 to 17 mm and are generally found in maturing and dried pods.
Young caterpillars are green, turning red later. Faeces in the form of granules are found inside the damaging pods.
What to do:
Apply biopesticides such as Bt or neem products. They usually give good control of pod borers, provided they are applied to pods before the young caterpillars enter into the pods. Once the caterpillars have entered the pods they are difficult to control and by then they have caused damage. Other plant derivatives reported to control pod borers are tephrosia and chilli/garlic.
Monitor regularly the crop to detect eggs and young caterpillars before they enter the pods
Conserve natural enemies. Ants, parasitic wasps and pirate bugs are important in natural control. Bird perches placed just above the crop canopy are also reported to reduce the numbers of pod borers
Green stink bug (nymphs and adults). Adults are about 1.2cm long. (Host: Pearl Millet) (c) Russ Ottens, University of Georgia, Bugwood.org
The pod sucking Riptortus bug (Riptortus dentipes) is about 1.5 cm long. (c) Georg Goergen, www.ecoport.org
Spiny brown bugs (Clavigralla spp.) measure about 1 cm in length. (c) A.M. Varela, icipe
Tip wilter / giant coreid bug (Anoplocnemis curvipes) is about 2.5cm long. (c) A.M. Varela, icipe
Pod sucking bugs are primary pests of pigeon peas.
The most common pod-sucking bugs are: giant coreid bugs (Anoplocnemis spp), spiny brown bugs (Clavigralla spp), Riptortus bugs (Riptortus spp) and green stink bugs (Nezara viridula).
These bugs suck developing seeds through the pod wall. The seeds become shrivelled with dark patches. Attacked seeds do not germinate and are not acceptable as food.
Fungal spores are sometimes transmitted with the mouthparts during feeding, resulting in rotting of the seeds.
The spiny brown bugClavigralla tomentosicollis is one of the most important pests of pigeon peas in Eastern Africa.
Sucking bug adults are difficult to control since they are very mobile and can invade crops from neighbouring sites.
What to do:
Immature bugs can be handpicked and destroyed.
Adults can be collected with insect nets and destroyed.
The main natural enemies of bugs are egg parasitoids, assassin bugs, ants and birds.
Spraying with aromatic plants (e.g. gums, lantana, khaki weed etc.) has been suggested to repel bugs (Elwell and Mass, 1995).
Neem-based pesticides reportedly reduce feeding by green shield bugs.
Western flower thrips (Frankliniella occidentalis). Close-up, immature thrips (left) and adults. Very much enlarged. Real size (0.9 to 1.1 mm) (c) M. Billah, icipe
Thrips are small (1.5 mm long), slender, brown insects with pale yellow hind wings that appear as a yellow line down the back of the body when the insect is at rest.
Adult thrips have characteristic wings; the transparent wings have a fringe of hairs around the outside edge standing out in the same plane as the wing.
Several species of thrips are common on pigeon peas in Eastern Africa and are considered important pests.
These thrips feed on leaves and flowers. Main damage is due to thrips feeding on flower buds and flowers. Heavy infestation can lead to shedding of buds and flowers.
However, according to reports from India, pigeonpea plants produce more flowers than the plant can sustain, so many are lost naturally and it is difficult to assess thrips damage (Ikisan, 2000).
What to do:
Conserve natural enemies. Predatory mites and pirate bugs are important for the natural control of thrips.
Monitor the crop regularly. Early detection is particularly important at the onset of flowering.
Whenever necessary spot spray the crop with botanicals. Some plant extracts (e.g. garlic, rotenone, neem, pyrethrum and a mixture of garlic and pepper etc.) are reported to control thrips. Spinosad, a bacterial derivative, is effective in controlling thrips.
Root-knot nematodes(Meloidogyne incognita / M. javanica) Roots of severely attacked (left) and healthy plant (right). Affected plants are normally stunted and eventually wilt and die. The most characteristic symptom is formation of root galls (knots) and these can be seen with the naked eye. Affected roots rot. (c) A. M. Varela, icipe
Affected plants are normally stunted and eventually wilt and die.
The most characteristic symptom is formation of root galls (knots) and these can be seen with the naked eye. Affected roots rot.
What to do:
Plant resistant varieties / lines, if available.
Plant in fields with no previous record of nematode infestation.
Rotate with cereals.
Amend soil with neem extracts.
A number of bio-products for control of nematodes are going through registration process in Kenya.
Cowpea seed beetle / Bruchid(Callosobruchus maculatus) adults are 2.-3.5 mm long. The adults emerge through windows in the grain, leaving round holes that are the main evidence of damage. (c) Clemson University – USDA Cooperative Extension Slide Series, www.insectimages.org
They are the most common and widespread insect pests in storage. Adults are 2-3.5 mm long.
They attack both pods in the field and seeds in storage. They attack nearly mature and dried pods.
Infested stored seeds can be recognised by the round exit holes and the white eggs on the seed surface.
Post-harvest losses are highly variable, but losses can be over 90%.
What to do:
Pods should be harvested as soon as they mature and the seeds sun dried before stored in clean beetle-proof containers.
A coating of edible oils or of inert clay can prevent further development of bruchids in the stored seeds.
Some
farmers in East Africa use wood ash in grain stored for food or seed
for planting, or chillies or smoke from cooking fire to preserve seeds
for planting.
Other farmers store unthreshed pods as a strategy to minimise grain damage by bruchids (Minja et al. 1999).
Leafhopper. Adults are small, about 2.5 mm long. Picture shows Empoasca fabae (c) Steve L. Brown, University of Georgia, Bugwood.org
assids (leafhoppers) have been reported to cause damage to pigeon peas in Kenya. These small (2.5 mm) green and very mobile insects occur on the upper and lower leaf surface.
The adults fly or hop away when disturbed. Nymphs resemble adults, but have no wings, and run sideways when disturbed. The eggs are inserted in the veins on the underside of leaflets.
Adults and nymphs feed by sucking on the leaflets. Attacked leaves become cup shaped and yellow at the edges. Heavy attacks result in the leaflets turning red-brown, with subsequent defoliation and stunting.
What to do:
Use neem kernel extract and other neem products.Neem treatments against aphids should be enough to control jassids at the same time.
The most important pests of pigeon peas are insects feeding on pigeon pea pods and seeds.
Surveys in Kenya, Malawi, Tanzania and Uganda (Minja et al., 1999) have shown that the most important pests of pigeon pea pods and seeds in the region are:
pod sucking bugs,
pod and seed boring caterpillars,
pod flies
Varieties that mature during the dry season have low damage levels (Snapp et al., 2003).
A number of caterpillars (e.g. hairy caterpillars and semiloopers), and beetles (e.g. weevils, and foliage beetles) that feed on foliage of other legumes and grain legumes also attack pigeon peas, but they are usually not important.
Pigeon pea (Cajanus cajan). Ripening pods (c) Courtesy EcoPort (http://www.ecoport.org): Cornell University
Pigeon pea (Cajanus cajan). Cultivated forms have larger seeds than their wild relatives and have been subjected to selection for larger seed. Larger seed used as fresh vegetables and medium sized genotypes for split pea production and milling. (c) Courtesy EcoPort (http://www.ecoport.org): R.P. Ellis
Pigeon pea used as green manure cover crop in Conservation Agriculture. On this smallholder’s farm, pigeon pea is used solely as a green manure cover crop in a soil recovery process. The next crop entering is maize. (c) Courtesy EcoPort (http://www.ecoport.org): Dirk Lange
Geographical distribution of Pigeon Pea in Africa. Updated on 8th July 2019. Source FAOSTAT.
General Information and Agronomic Aspects
Pigeon pea is an important grain legume crop of rain-fed agriculture in the semi-arid tropics. Main pigeon pea producing regions are the Indian sub-continent, Central America and Southern and Eastern Africa.
Pigeon pea is produced as a vegetable or export grain crop in southern and eastern Africa. In Kenya, pigeon pea is the third most widely grown pulse crop, and it is one of the fastest growing cash crops with an annual growth rate of 3% in the last decade.
Green pigeon pea is being exported from Kenya to Europe (Snapp et al, 2003). The dry grain is also an important local pulse and export commodity in several African countries (Kenya, Malawi, Mozambique, Tanzania and Uganda) (Minja, et al, 1999).
Pigeon pea is a perennial shrub that is commonly grown as an annual crop. It has very slow initial development (up to 2 months after planting). With a deep taproot, pigeon peas are able to take up nutrients and water from lower subsoil layers.
Therefore, in crop mixes they hardly compete with the companion crops. This crop grows and yields well under conditions of low rainfall and poor soil.
Pigeon pea is well balanced nutritionally and an excellent source of protein. It is eaten as a vegetable (immature pods or green pea) or as dried grain (cooked and eaten as dhal, dry split cotyledons).
The crop has many other uses: the wood is used as fuel, and the leaves and husks provide livestock feed.
Pigeon pea is useful as tall hedges on dry soil and on the bunds of paddy fields. The branches and stems can be used for baskets and firewood. It is often grown as a shade crop, cover crop or windbreak.
After establishment, pigeon pea improves the soil by its extensive root system. The bacterium Rhizobium that lives on the roots of the pigeon pea is able to fix nitrogen and thus to improve soil fertility.
Fallen leaves are used as mulch. Traditional uses as medicine are many, e.g. young leaves are applied to sores, herpes and itches.
Climatic conditions, soil and water management
Optimum temperatures for pigeon pea cultivation range from 18 to 38degC. Pigeon pea does not tolerate frost. Above 29degC, soil moisture and fertility need to be adequate.
Rainfall optimum is 600-1000 mm/year. Pigeon pea is a short day plant. Flowering is triggered by short days, whilst with long days plants grow vegetative. It is sensitive to high salinity and to water logging. It flowers well where rainfall is 1500 to 2000 mm.
On deep, well-structured soil it will grow where rainfall is 250 to 370 mm. Pigeon pea is rarely found above altitudes of 2000 m.
Drained soils of reasonable water-holding capacity and with pH 5-7 are favourable for its growth. Pigeon pea does not tolerate shallow soils or water logging.
Pigeon pea varieties in Kenya and their characteristics:
Variety
Maturity period (days)
Potential yield (90 kg bags/acre)
Characteristics
“Kat 60/8”
135-150
5-7 for one season (13 for 2 seasons)
Grains
are white with brown spots and smaller seed size than local races.
Grows between 0-1800 m above sea level and performs well where
temperatures are high. Tolerant to Fusarium wilt and leaf spot diseases.
Susceptible to pod sucking bugs and pod borers.
“Kat 81/3/3”
170-185
6-11
Tolerant
to wilt, pod sucking bugs and pod borers. Cream white grain with large
brown patches. Adapted to medium and higher altitudes (over 900 m above
sea level)
“Kat 777”
160-180
6-10
Oval white seeds. Adapted to medium and higher altitudes (above 900 m above sea level)
“ICPL 89091”
120
4 for one season, 8 for 2 seasons
It
is grown in the same range of altitude as “KAT 60/82” but is more
adapted to the more humid coastal zones. Performs best in pure stands at
quite high density.
“Mbaazi-1”
105-120
4 in one season
Grows between 600 and 900 m above sea level. Grain greyish in colour. Should be grown as a pure stand
“Mbaazi-2”
150-180
6
Adapted to medium and high altitudes (900 – 1800 m). Grain greyish in colour. Tolerant to insect pests and Fusarium wilt
“Mbaazi-3”
90-105
6
Performs well at altitudes 10-1500 m. Grain greyish in colour
“Local races”
Examples of pigeon pea varieties in Tanzania
“Komboa”
(performs well below altitude of 1500 m; early maturing about 90 – 100
days; grain mottled cream and brown; potential yield of about 4 t/ha)
“Mali”
(adapted to altitude between 500 – 1500 m; medium maturity: 130 – 150
days; grain yield 1.0 – 3.0 t/ha; resistant to Fusarium wilt; tolerant
to insect pests and drought)
“Tumia” (performs well below 1500 m
altitude; recommended for areas with low to medium rainfall (250 – 600
mm); maturity less than 150 days; grain yield of 1.8 – 2.4 t/ha; white
grain colour; susceptible to Fusarium wilt; tolerant to drought)
“Luwe 1 – 5” (maturity of about 159 days; grain yield of 1.2 t/ha; white grain colour; susceptible to Fusarium wilt)
Propagation is by seed, stem cuttings rarely succeed. Pigeon pea varieties differ not only in form of seeds, colour and taste, but also in growth habit, time of flowering and susceptibility towards pests and diseases. Seed rate: 20-25 kg per ha (8-10 kg per acre)
Land preparation
Pigeon pea thrives best in
seedbeds prepared by deep ploughing and cultivations to reduce weeds.
Seeds should be sown in rows with spacing of 30-50 cm x 75-150 cm and 10
cm deep. There is no standard spacing – spacing depends on variety,
soil type and production system. In dry areas, and especially in
coarse-textured, infertile soils, farmers use wide spacing between
plants to limit competition. Plants are fairly slow to start and weed
control for the first two months is important in crop establishment.
Once plants are established they grow vigorously.
Husbandry
Weeds must be controlled to facilitate slow initial growth. Wind may bend the plants but staking is not practised. Response to fertilisers is seldom economic.
In Eastern Africa, the crop is cultivated on marginal lands by resource-poor farmers, who traditionally grow landraces. Inputs such as fertilisers, irrigation and pesticides are hardly used.
Intercropping
In intercropping, the crop performs well with 2 rows of cereals (e.g. sorghum, millets), cotton or groundnut. After harvest of the intercrop, long-duration pigeon pea continues to grow and protects the soil.
Pigeon pea is regarded as a good plant for restoration of fertility and is used in a rotation with crops such as maize-groundnut-tobacco-pigeon pea for three to four years in Uganda. One of the advantages of pigeon pea is the increased growth of the grass interplanted with it.
In Uganda, it is usually sown in alternate rows with sesame or African finger millet (Eleusine coracana), and in Malawi with maize. In Tanzania, the main intercrop is cassava. In Kenya, sorghum and maize are the most common intercrops with pigeon pea.
However, due to its high demand, there is a tendency to move away from traditional intercropping to monocropping. In Ukambani and Coastal strip, Kenya, the crop is grown commercially in large plots.
Harvesting
The crop is usually cut near the ground when most pods are mature, or mature pods are picked individually. Green pods are picked over a long period in home gardens or hedge crops.
Ratoon cropping is mostly practised in pigeon pea producing areas in Kenya. After harvest the stems are cut back to facilitate re-growth and a second crop is harvested in the subsequent season.
Entire air-dried plants or pods are threshed, usually by hand or with cattle, and seed is cleaned. Clean bins prevent insect attack, which can be considerable. Storage as split peas reduces bruchid attacks.
Processing includes dhal making, either wet (after sprinkling heaps of seed) or dry, by milling.
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Contacts for cowpea seeds:
Industrial Crop Research Institute, Mtwapa: icri@kalro.org, +254 (20) 2024751
